It is recognized by those skilled in the art that tensile strained silicon (Si) material provides for increased electron mobility and improved performance with respect to n-channel metal oxide semiconductor (MOS) field effect transistor (FET) devices. However, many integrated circuit designs require the use of p-channel MOSFET devices as well. Circuits of this type are commonly referred to as complementary metal oxide semiconductor (CMOS) circuits. Unfortunately, tensile strained silicon material is detrimental to the operation of p-channel MOSFET devices which instead prefer compressive strained silicon-germanium (SiGe) material to boost hole mobility and improve performance. The integration of tensile strained silicon material and compressive strained silicon-germanium material on a common substrate in support of the fabrication of CMOS circuits has proven to be a challenge.
The prior art teaches the formation of integrated circuits which utilize FinFET type field effect transistors. The FinFET transistor comprises a channel region which is oriented to conduct an electrical current parallel to the surface of the substrate. The channel region is provided in an elongated section of semiconductor material referred to as a “fin.” The source and drain regions of the transistor are formed in the elongated section on either side of the channel region. A gate is placed to straddle over and on both opposed sides of the elongated section at the location of the channel region to provide control over the conductive state of the transistor. This FinFET design is well suited for manufacturing a multi-channel transistor in which multiple elongated sections are formed in parallel to define neighboring channel regions which are separated from each other by an intermediate gate portion of the transistor gate spanning with a perpendicular orientation over the multiple elongated sections.
It is preferred for the fabrication of CMOS circuits with FinFET devices for the elongated section of semiconductor material (i.e., the fin) of the n-channel MOSFET devices to be made of tensile strained silicon material and for the elongated section of semiconductor material (i.e., the fin) of the p-channel MOSFET devices to be made of compressive strained silicon-germanium (SiGe) material. It has proven difficult, however, to obtain relaxation of the tensile strained silicon material on a substrate in order to support the formation of compressive strained silicon-germanium material. In other words, provision of both tensile strained silicon material and compressive strained silicon-germanium material on a substrate for supporting fins of CMOS circuits is challenging.
A need accordingly exists in the art for a method of manufacture which can integrate both tensile strained silicon material and compressive strained silicon-germanium material for the formation of CMOS FinFET devices.